EP2039939B1 - Method for monitoring an energy conversion device - Google Patents

Description

The invention relates to a method for monitoring an energy conversion device, which consists of several functionally linked functional units. Such energy conversion devices in the context of the invention may be, for example, electric motor driven centrifugal pump units, electric motor driven compressors, equipment equipped therewith or the like. They consist of several functionally linked functional units, such as electric motor and centrifugal pump or electric motor and positive displacement pump or combustion engine and electric generator. Such energy conversion devices are used today in almost all technical but also domestic applications.

Although, in the course of dwindling resources, efforts are always made to build machinery, equipment or other energy conversion facilities so that they work with the highest possible efficiency for a long time, but in practice often poses the problem that the initial high efficiencies diminish and the Device continues to operate, although it no longer has the desired efficiency for a long time. This phenomenon can be observed, for example, in heating circulation pumps or in refrigerators. An exchange typically only occurs if a defect is evident or if the device completely fails the designated service.

In many such cases, however, it would make economic sense to replace the device beforehand or at least to replace or repair the defective or defective functional unit.

Out DE-A-10 2007 009 301 Although already a generic method for a pump to the prior art, in which the flow value is determined by a controller during operation of the pump based on the speed and based on previously tabulated values and compared with a flow threshold, but the monitoring described therein serves for the determination of dangerous operating conditions and not for monitoring the efficiency.

Out EP-A-1 564 411 With all features of the preamble of claim 1, there is a comparable prior art method which monitors the proper operation of the pump.

Against this background, the invention has the object, a generic method for monitoring an energy conversion device, which consists of a plurality of functionally interconnected functional units to improve, in particular to the effect that not only a false state, but also a deterioration in efficiency is detected. Furthermore, corresponding energy conversion devices for carrying out the method according to the invention are to be formed.

The procedural part of this object is achieved by the features specified in claim 1. Aggregates and a system for carrying out the method according to the invention are specified in claims 13 to 16, advantageous embodiments in the dependent claims.

The solution according to the invention provides a method for monitoring an energy conversion device, which consists of a plurality of functionally linked functional units, in which power-dependent variables of at least one functional unit are automatically acquired and / or calculated at intervals and with each other or with values derived therefrom and / or or are compared with predetermined values and a corresponding signal is generated as a function of this comparison. According to the invention, power-dependent variables of at least two functionally connected functional units, preferably of all functional units, are automatically detected and / or calculated at intervals, the power-dependent output variables or variables derived therefrom of the one functional unit forming the power-dependent input variables of the function unit downstream of this functional unit. Based on this signal can then be determined whether the device is still working with the desired effectiveness, possibly provide one or more functional units insufficient performance or work with a reduced efficiency and thus determined whether the device is repair or replace. By means of this combination mathematical models can be used in the calculation and the above-mentioned monitoring tasks can be reliably ensured on the basis of only comparatively less measurable variables.

The basic idea of the method is to monitor at least one functional unit at intervals with regard to its efficiency and to display the result by means of a signal or to make it automatically evaluable. In the simplest form, power-dependent variables of a functional unit are automatically detected at intervals over time and compared with predetermined values determined beforehand or derived therefrom. Thus, for example, by comparing an immediately after commissioning of the device determined performance-dependent size of one of its functional units and comparison with predetermined values are determined whether the factory default performance is provided or not. It can then be determined in further, preferably larger time intervals by comparing at least one power-dependent variable, whether and to what extent the efficiency of the functional unit has deteriorated. It is advantageous according to the invention, not only one, but it is suitably monitored all the efficiency of the device substantially determining functional units in the manner described above. By monitoring the performance and corresponding signal processing, an energy conversion device, ie in particular an aggregate, a machine or a system can self-learning determine and display its individual performance characteristics, the resulting operating behavior, life expectancy and the like.

Performance-dependent variables in the sense of the present invention are those which stand in some connection with the performance characteristic of a functional unit. Thus, for example, in discontinuously operating units, such as the compressor of a refrigerator, and the timing of the switching on and off a performance-dependent size in the sense of the present invention.

Advantageous embodiments of the method according to the invention as well as devices operating according to the method of the invention are specified in the further claims and the following description and drawing.

The efficiency monitoring according to the invention of the device or at least individual functional units of the device can be carried out comparatively easily if the functional units are always in the same position Run operating point, since then typically a reading is sufficient to determine the intended or decreased power / efficiency of each unit. However, this is more complicated if an energy conversion device such as a heating circulation pump is to be monitored. Such aggregates typically consist of the functional units engine and centrifugal pump, wherein the centrifugal pump typically constantly changes its operating point, since the pipe network resistance of the heating system changes due to external influences. In order to have comparable performance-related variables here, it is appropriate to use an electric-mechanical motor model and the variables resulting from a mechanical-hydraulic pump model at the motor-pump interface to determine the power level of the pump set , Alternatively, the determination can also take place in that two hydraulic variables of the pump, typically the flow rate and the delivery head, are determined and equated with the mechanical output delivered by the engine via a corresponding model calculation.

It is particularly advantageous in such facilities, in which the operating points change constantly and is therefore assumed that in temporally spaced measurements of all probability not the same operating point is reached again in a short time to perform several measurements and based on the thus determined Operating points to determine performance-dependent, possibly multi-dimensional surface curves at the interfaces of the functional units to each other and to compare with previously determined. In this case, these calculated surfaces are advantageously approximated using a Kálmán filter, so that even with comparatively few measurements, the respective performance-determining surface can be determined with sufficient accuracy. It can then be the distance of such In a longer time interval determined areas at a certain operating point or spanned between the surfaces volume as a measure of the efficiency change, typically the efficiency drop can be used.

Advantageously, the method according to the invention is carried out during the normal operation of the device, that is to say in the case of a pump unit during the intended conveying operation, wherein the time interval for detecting the quasi-simultaneous operating points for determining the course of the area may be in the range of, for example, minutes, whereas the time interval after a comparative measurement is performed, may be in the daily, weekly or monthly range, depending on the device type. Comparatively long intervals are z. As result in heating circulation pumps, whereas short intervals in compressors, especially for cooling systems may be appropriate because with such a monitoring method not only a deterioration in efficiency, but also a possible expected failure of the device can be detected.

The time interval in which the performance-dependent variables to be compared are thus determined depends both on the type of machine and on the intended use. The comparison is, however, expediently based on the previously acquired variables or predetermined values, the latter method having the advantage that a poor function can thus already be detected during commissioning.

With significantly lower metrological and computational effort, the method according to the invention can be carried out when first recorded and stored a determining the power consumption of the motor electrical size of the motor and at least one of the hydraulic operating point of the pump-determining variable be waited and for the subsequent comparison measurement until the previously detected hydraulic operating point is reached again and then the power consumption of the engine determining variables of the engine are detected and compared with the first stored. Then, a direct comparison can be made without operating point deviations and thus the aforementioned surface curves must be determined.

Alternatively, the variables acquired later for comparison measurement can also be detected at any operating point of the installation if the acquired variables are transferred based on a mathematical electrical motor model and / or a mathematical-hydraulic pump model, i. be converted to operating point independent variables and then compared with the stored variables or vice versa, so that a comparison of the power-determining variables is possible regardless of the operating point.

Advantageously, according to the invention, the method is used only after a predetermined time has elapsed, this predetermined time corresponding at least to the running-in time of the unit, in particular of the pump unit. This is useful so that adjust the mechanical parts of the unit, any Einfahrwiderstände be overcome in the camps and then after the break-in an initially quasi-stationary operating condition can be achieved, which forms a basis for the normal performance-determining characteristics of the device, so that only deviations be detected from this state later.

In this case, it is particularly advantageous if, after the expiry of the predetermined time, ie typically the break-in period, at least one operating profile is detected automatically and the expected energy consumption is determined taking into account the possibly determined change in efficiency and indicated by appropriate means. With this method, it is possible to automatically determine after the break-in period whether the unit will meet the values specified in terms of performance / efficiency or what additional changes in energy consumption will be expected due to a deterioration in efficiency.

According to an advantageous development of the method according to the invention, it is not necessary for a comparison measurement to approach the same operating point. Rather, based on a plurality of operating points, a surface course having a multidimensional model character and dependent on the performance of a functional unit can be determined and stored again at temporal intervals and stored and compared with the or a previously determined one, the distance of the surface curves in a predetermined operating point or operating range or the volume spanned between the surface sections are used as a measure of the change in efficiency. Such an evaluation is particularly advantageous because it can be done during continuous operation without any intervention in the performance of the machine. Such a method is particularly advantageous in centrifugal pump units, as used for example as heating circulation pumps, which usually run on constantly changing operating points. To determine the course of the surface on the basis of the operating points, a Kálmán filter is advantageously used. This iteration method makes it possible to determine the course of the area sufficiently accurately with only a comparatively small number of measured operating points in order to be able to detect the deviations in question and to be able to determine them quantitatively.

The inventive method can in principle in any energy conversion devices consisting of several functional with each other linked functional units are used for monitoring. Particularly advantageous is the use of centrifugal pump units, compressors, heating systems, refrigerators, freezers and the like, which are typically operated over years and decades, without a decrease in efficiency would notice or announces a failure. Thus, the monitoring method according to the invention is both suitable for detecting and displaying a poor running, ie a deterioration in efficiency, which makes early replacement of the unit or at least one functional unit of the unit appear economically sensible, as well as, for example, in freezers or freezers of particular advantage to be able to display the anticipated failure of the unit to provide timely replacement. Even with larger machines whose stoppage entails economic consequences, the inventive method can be used effectively to indicate an imminent failure in advance. It goes without saying that appropriate characteristic values are then suitably specified which were previously determined in the laboratory test, so that the downtimes can at least roughly be determined on the basis of the change in efficiency or the change in power of the machine.

The method according to the invention can advantageously be implemented in the form of a software program in the digital control and regulating electronics which are present anyway in modern units. In pump units and compressors, such control and regulating electronics can be provided both in the unit itself and in the terminal or terminal box of the unit.

Advantageously, the method according to the invention in a centrifugal pump unit with an electric motor and a centrifugal pump driven by it in a device provided there for monitoring the performance of at least one functional unit of the unit applied. Even with a compressor unit with an electric motor and a positive displacement pump driven therefrom, such a device according to the invention for monitoring the power characteristic, in particular for the efficiency detection and monitoring can be provided. Advantageously, a cooling unit can be provided with an electric motor, with a positive displacement pump driven therefrom, with an evaporator and with a capacitor with a device for monitoring the performance, which operates according to the inventive method, wherein the monitoring of the performance characteristics not only on engine and Positive displacement pump limited, but advantageous evaporator and condenser includes.

In particular, in refrigerators, a reduction in the efficiency is determined by the fact that the duration of the compressor is monitored after installation of the device. This can be done, for example, by determining the running time within 24 hours and then comparing it later, for example after six months, with the resulting runtime within 24 hours. It is to be assumed in the simplest form that due to constant environmental conditions and user behavior an increasing duty cycle is due to a deterioration in the efficiency of the system. More precise conclusions can be determined by an analysis of the time course of the compressor runtime.

Similarly, in a heating system, a device for monitoring the performance of the burner and at least one of these heatable water cycle can be provided in order in this way, for example, combustion residues on the primary heat exchanger and concomitant efficiency deterioration to be able to capture. Here, by attaching a corresponding signal lamp thus also an indication of the required cleaning service will be given, which can thus be determined as needed.

Appropriately, the device is designed so that it automatically starts after a predetermined time after commissioning of the unit or the system with the detection and storage for monitoring the performance characteristics, in particular for determining the effectiveness and monitoring sizes and at appropriate intervals again these sizes recorded and compared with the pre-stored and / or the originally stored variables and displays a possibly impermissibly high deviation. According to an embodiment of the invention, the device therefore advantageously has a measured value memory in which at least the variables detected at the beginning of the measurement or variables derived therefrom are stored.

Appropriately, the machine is monitored as far as possible in its entirety by the method according to the invention. However, it may also be sufficient to monitor only one functional unit of the machine. This will be particularly useful if the machine has a functional unit that typically fails significantly before all other functional units due to wear or otherwise.

It is particularly advantageous if several or preferably all functional units of an energy conversion device, ie a machine, an aggregate or a system, are detected in order to be able to allocate these selectively to one or more functional units in the event of a deterioration in efficiency, and then selectively only this functional unit or functional units to repair or exchange. This will be economically viable, especially for larger machines.

Fig. 1

anhand eines Schaubilds das grundlegende Prinzip eines mit Leistungsflächen arbeitenden erfindungsgemäßen Überwachungsverfahrens,

Fig. 2 a

das Überwachungsverfahren nach Fig. 1, dargestellt anhand eines Kreiselpumpenaggregates,

Fig. 2 b

ein alternatives Überwachungsverfahren für eine Kreiselpumpe,

Fig. 2 c

eine weitere Variante eines Überwachungsverfahrens für eine Kreiselpumpe,

Fig. 3

ein Überwachungsverfahren, dargestellt anhand eines Kompressors,

Fig. 4

ein Überwachungsverfahren, dargestellt anhand eines Kühlgeräts und

Fig. 5

ein Überwachungsverfahren, dargestellt anhand einer Heizungsanlage.

The invention is explained in more detail with reference to embodiments shown in the drawing. Show it:

Fig. 1

on the basis of a diagram, the basic principle of a monitoring system operating according to the invention with power surfaces,

Fig. 2 a

the monitoring process Fig. 1 represented by a centrifugal pump assembly,

Fig. 2 b

an alternative monitoring method for a centrifugal pump,

Fig. 2 c

a further variant of a monitoring method for a centrifugal pump,

Fig. 3

a monitoring method, represented by a compressor,

Fig. 4

a monitoring method, illustrated by means of a refrigerator and

Fig. 5

a monitoring procedure, represented by a heating system.

In Fig. 1 is an energy conversion device consisting of the functional units 1 and 2 shown by way of example for a variety of machines, systems and units. In the illustrated embodiment, the functional units 1 and 2 are independent of each other supervised. In this case, first of all the power P _{1 received} by the functional unit 1 is dependent on one or more variables x ₁ recorded and stored, as in Fig. 1 represented by 3. The variables x ₁ are through u ₁ and y ₁ , so that the area shown in FIG. 3 corresponds to the energy balance of the functional unit 1 at the entrance. Accordingly, a power P ₂ sets in at the output, which in turn depends on the variables x ₁ is. This area is shown in FIG. The functional units 1 and 2 are functional, z. B. via a shaft connected to each other, which is why the representation 4 of the representation 5 corresponds to the power P ₂ here in dependence on x _{2 defined} according to the energy balance at the input of the functional unit 2, depending on the variables u ₂ and y ₂ . At the output of the functional unit 2 is a power P ₃ , as shown in FIG. 6 and dependent on x ₂ is.

The surfaces marked by hatching in FIGS. 3 to 6 are determined at the beginning of the method. This can be factory-made or only after some time in operation. This can be done as an initialization process or during operation. In any case, it takes place at a time t ₁ , which, if several operating points are to be detected, can also represent a time range. At a time t ₂ , an energy balance at the input of the functional unit 1, at the output of the functional unit 1, at the input of the functional unit 2 and at the output of the functional unit 2 is then created in the same way. The corresponding representations are marked 3 ', 4', 5 'and 6'. By comparing these at the time t ₂ , which may also be a time range, determined sizes or areas with the determined and stored at time t ₁ sizes or areas efficiency reductions of individual functional units 1, 2 can be detected wherein the distance of the hatched areas in 3 and 3 'and 4 and 4' and 5 and 5 'and 6 and 6', respectively, at a predetermined operating point determined or the volume spanned between these areas is determined and when a predetermined value is exceeded, a signal is generated, which indicates to the user that in the machine efficiency deterioration has taken place, which is an exchange or a repair or an immediate replacement or an immediate repair expedient. Here, by grading the values, different signals may be generated, for example, a first warning signal indicative of a certain level of reduced efficiency and a second warning signal indicative of such a reduction in efficiency requiring replacement or repair. Since the functional units 1 and 2 are monitored separately from one another, it can furthermore be determined which of the functional units is wholly or partially responsible for the reduction in efficiency.

• Variable:
  • q ∼ Volumenstrom durch die Pumpe [m³/h]
  • Δp ∼ von der Pumpe aufgebauter Differenzdruck [bar]
  • ω _r ∼ Geschwindigkeit der die Pumpe antreibenden Welle [U/sec]
  • T_e ∼ Drehmoment der Welle [Nm]
  • V ∼ Versorgungsspannung [V]
  • I ∼ Versorgungsstrom [A]
  • φ ∼ Winkel zwischen der Versorgungsspannung V und dem Motorstrom I [U]
  • ω _e ∼ Versorgungsfrequenz [U/sec]
  • P ₁ ∼ dem Motor zugeführte elektrische Leistung [W]
  • P ₂ ∼ mechanische Leistung an der Motorwelle [W]. Die Leistung P₂ ist proportional zum Schlupf s des Motors. Dies ist P₂ ∞ s.
  • P₃ ∼ hydraulische Leistung der Pumpe [W]
  • ηm ∼ Motorwirkungsgrad
  • ηp ∼ Pumpenwirkungsgrad

How this can look like in a specific application is, for example, based on Fig. 2a . b and c shown. Shown there is a device consisting of an electric motor 1a and a pump 2a, which feeds a consumer 7. The electrical power absorbed by the motor 1a is indicated by P ₁ . The motor converts the electric power into a torque T _e at a rotational speed ω _r . This pending at the output of the motor 1a mechanical power P _{2 also} represents the pending at the entrance of the pump 2a mechanical power P ₂ , which is converted within the pump into a hydraulic power P ₃ , by the pump between suction and pressure side generated pressure difference .DELTA.p and the flow rate through the pump q is determined. To the on the basis of Fig. 2a From device 1a and pump 2a completely monitor existing device, it is expedient to determine at the respective interfaces surfaces, which the performance of the respective functional unit in every possible Operating point, respectively at the input and at the output of the same.
The formulaic relationship is as follows:

• Variable:
  • q ~ Flow rate through the pump [m ³ / h]
  • Δp ~ differential pressure built up by the pump [bar]
  • ω _r ~ speed of the shaft driving the pump [rev / sec]
  • T _e ~ Torque of the shaft [Nm]
  • V ~ supply voltage [V]
  • I ~ supply current [A]
  • φ ~ angle between the supply voltage V and the motor current I [U]
  • ω _e ~ supply frequency [U / sec]
  • P ₁ ~ electric power supplied to the motor [W]
  • P ₂ ~ mechanical power at the motor shaft [W]. The power P ₂ is proportional to the slip s of the motor. This is P ₂ ∞ s .
  • P ₃ ~ hydraulic power of the pump [W]
  • ηm ~ motor efficiency
  • ηp ~ pump efficiency

$$P_1=\mathit{VI}\cos \left(\phi \right)$$

$$P_2={\omega }_r{T}_e$$

$$P_3=\mathit{\kappa \; q\; \Delta p}$$

$${\eta }_m=\frac{P_2}{P_1}$$

$${\eta }_P=\frac{P_3}{P_2}$$

These variables are linked as follows: $$s=\frac{{\omega }_e-{\omega }_r}{{\omega }_e}$$

$${\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_1=\mathit{VI}\cos \left(\phi \right)$$

$${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\omega }_r{T}_{\mathrm{<figure-callout\; id="3"\; label="e\; P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">e\; </figure-callout>}}$$

$$P_{}$$$${}_3=\mathit{\kappa \; q\; \Delta p}$$

$${\eta }_m=\frac{P_2}{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}$$

$${\eta }_P=\frac{P_3}{{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2}$$

(Gleichung 8)
wobei vorausgesetzt wird, dass die Versorgungsspannung durch denThe mathematical description of the power of the motor defining in all operating points area according to representation 8 thus results from the following equation: $${\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_1\left({\omega }_e,s\right)=v_s•{\left[{\mathit{IR}}_s+{\mathit{J\omega }}_e\left(L_{\mathit{is}}-L_m\right)-{\mathit{J\omega }}_e{L}_m{\left(\frac{R_r}{s}+{\mathit{J\omega }}_e\left(L_{\mathit{ir}}+L_m\right)\right)}^{-1}{\mathit{J\omega }}_e{L}_m\right]}^{-1}{v}_s$$

(Equation 8)
assuming that the supply voltage through the

gegeben ist. Rs (Statorwiderstand), L_ls (induktive Verluste des Stators), L_m (magnetische Induktion), L_lr (induktive Verluste des Rotors), R_r (Rotorwiderstand) und $\mathit{J}\left(\mathrm{Matrix}\left[\begin{array}{cc}0& -1\\ 1& 0\end{array}\right]\right)$

sind die Konstanten des Motors.vector $\left[\begin{array}{c}{V}_{\mathit{sd}}\\ V_{\mathit{sq}}\end{array}\right]=\left[\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">K</figure-callout>}}_1{\omega }_e+K_0\\ 0\end{array}\right]$

given is. Rs (stator resistance), L _ls (inductive losses of the stator), L _m (magnetic induction), L _lr (inductive losses of the rotor), R _r (rotor resistance) and $\mathit{J}\left(\mathrm{matrix}\left[\begin{array}{cc}0& -1\\ 1& 0\end{array}\right]\right)$

are the constants of the engine.

beschrieben werden, in welcher die Konstanten a_T2, a_T1, a_T0 und B Pumpenkonstanten sind.The power at the inlet of the pump 2a according to illustration 9 can be known by the pump equation $$P_2\left(q,{\omega }_r\right)=-a_{P2}{\mathrm{<figure-callout\; id="2"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^2{\omega }_r+a_{P2}\mathrm{<figure-callout\; id="2"\; label="q\; \omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q\; </figure-callout>}{\omega }_r^{}{}_2^{}+a_{P0}{\mathrm{<figure-callout\; id="3"\; label="\omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}}_r^{}+B{\omega }_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2$$

in which the constants a _T2 , a _T1 , a _T0 and B are pump constants.

The power present at the output of the pump 2a as shown in FIG. 10 can be described by the following equation: $$P_3\left(q,{\omega }_r\right)=-a_{p2}{\mathrm{<figure-callout\; id="3"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^3{\omega }_r+a_{p2}{\mathrm{<figure-callout\; id="2"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^2{\omega }_r+a_{p0}\mathrm{<figure-callout\; id="2"\; label="q\; \omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q\; </figure-callout>}{\omega }_r^{}{}_2^{}+p_{\mathit{offset}}q$$

In this equation, the constants are a _p2 , a _p1 , a _p0, and p _offset .

Based on the illustrations 8, 9 and 10 in Fig. 2a illustrated three-dimensional areas, which describe the power at the interfaces before, between and behind the functional units 1 a and 2 a, are detected and stored at a time t ₁ . The detection typically occurs during normal operation for a short period of time which is negligibly small with respect to the monitoring interval (time from T ₁ to t ₂ ), after which, after a longer period of time, namely at time t _2, this process is repeated so that the surfaces according to the representations 8 ', 9' and 10 'result. The surfaces 8 and 8 'as well as 9 and 9' and finally 10 and 10 'are compared with one another at the time t ₁ and t ₂ . If the surfaces match, the unit will work unchanged. On the other hand, if two of these surfaces are spaced apart at one operating point, then one of the functional units has changed in performance, typically deteriorating. If, for example, a distance between the surfaces according to FIGS. 10 and 10 'and otherwise matching surfaces are determined, then it can be assumed that, although the motor 1a operates with undiminished efficiency, an operation which changes the efficiency has taken place within the pump 2a , Conversely, with a change in the surfaces according to the representations 9 and 9 'for constant pump performance characteristic but changed engine efficiency can be concluded.

In monitoring as they are based on Fig. 2a is displayed, there is a performance monitoring in front of and behind each functional unit 1 a, 2a. However, this can be dispensable depending on the application. Also, it is not absolutely necessary to determine the surface curves having the multi-dimensional and model character representing the input or output power, as defined by equations 8, 9 and 10, but rather, like the embodiment according to FIG Fig. 2b clarified, for example, in place of the power P ₃ as shown in Figure 10 in Fig. 2a Alternatively, the hydraulic power characteristic can be determined, that is, the differential pressure applied by the pump 2a as a function of the drive speed ω _r and the flow rate q. Which is detected and stored at time t ₁ . The multi-dimensional area listed in FIG. 10 a and the area listed at time t ₂ in representation 10 a 'are each defined by the equation. $$\mathrm{\Delta }\mathit{p}\left(q,{\omega }_r\right)=-a_{p2}{\mathrm{<figure-callout\; id="2"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^2+a_{p2}{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^1{\omega }_r+a_{p0}{\mathrm{<figure-callout\; id="2"\; label="\omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}}_r^{}+p_{\mathit{offset}}$$

Based on Fig. 2c is another way of monitoring such a pump unit consisting of the functional units 1a and 2a shown. As illustrated in FIG. 11, the power P _{1 is} detected there as a function of ω _e and Q as shown in FIG. 8 a and is compared with the corresponding power as shown in FIG. 8 a 'at a time interval between t ₁ and t ₂ . Also, the power P ₂ is determined there as a function of Δ _p and ω _r , as the illustration according to 9a or 9a 'illustrates. Finally, in the case of Fig. 2c monitoring concept shown the efficiency of the motor η _m and the efficiency of the pump η _p directly monitored, as the representations 11a and 11b and 11a 'and 11b' illustrate. These differences are only intended to clarify that there are a variety of ways of monitoring the performance of the entire device but also the functional units thereof, as described above with reference to the from the functional units engine 1a and Pump 2a existing centrifugal pump unit has been clarified.

The efficiency of the motor η _m is the quotient of P ₂ and P ₁ and is dependent on ω _e (the supply frequency ) and s , the slip of the motor. The motor efficiency is in Fig. 2c in the representation 11 a represented by the area in the diagram in each operating point. In illustration 9a, the power P _{2 is shown} as a function of Δp and ω _r . This results in the efficiency of the pump η _p as a function of the pump speed ( ω _r ) and the delivery rate q , as illustrated by the surface shown in FIG. 11 b. In FIG. 8a, the power P _{1 of} the motor 1 a is likewise represented in the form of a surface as a function of the supply frequency and the flow rate of the pump. Analogous to Fig. 1 are the basis of the surfaces 8a, 9a, 11a and 11b shown performances and efficiencies at time t _{1 were} determined and stored, whereas at time t ₂ corresponding comparison surfaces have been determined, as a measure of the change in efficiency of the distance of the surfaces in the Representations 11a and 11 a 'and 11 b and 11 b' are used. For example, if the efficiency of the pump 2a decreases in the course of time t ₁ to t ₂ due to bearing damage, the surfaces in the representations 11 a and 11 a 'will be in one another, whereas the surfaces in the representations 11 b and 11 b' a clear distance from each other, based on an operating point. Instead of this distance, a volume can also be defined.

• p_in ∼ Eingangsdruck am Kompressor [bar]
• p_out ∼ Ausgangsdruck am Kompressor [bar]
• T_in ∼ Eingangstemperatur am Kompressor [°K]
• T_out ∼ Ausgangstemperatur am Kompressor [°K]
• ω _r ∼ Drehzahl der den Kompressor antreibenden Welle [U/sec]
• P₁ ∼ vom Motor aufgenommene elektrische Leistung [W]
• P₂ ∼ Leistung an der Antriebswelle [W]. Die Leistung P ₂ ist proportional zum Schlupf des Motors s. Dies ist P ₂ ∞ s.

Based on Fig. 3 shows by way of example how a compressor can be monitored with the method according to the invention. The compressor has a functional unit 1b in the form of a motor and a functional unit 2b driven in the form of a positive displacement pump which feeds a consumer 7b. Again, at a time t _1, a motor power representing surface according to Representation 12 as well as a surface representing the pumping capacity determined according to representation 13 and stored at a time interval, for example, at time t ₂ , according to the representations 12 'and 13' based on current values at time t ₂ and compare with the stored, also here the distance of the surfaces according to the representations 12 and 12 'or 13 and 13' and the volume spanned therebetween is used as a measure of the efficiency deterioration. The computational relationships are as follows:

• p _in ~ inlet pressure at the compressor [bar]
• p _out ~ outlet pressure at the compressor [bar]
• T _in ~ inlet temperature at the compressor [° K ]
• T _out ~ Output temperature at the compressor [° K ]
• ω _r ~ speed of the shaft driving the compressor [rev / sec]
• P ₁ ~ electric power absorbed by the motor [W]
• P ₂ ~ Power at the drive shaft [W]. The power P ₂ is proportional to the slip of the motor s . This is P ₂ ∞ s .

$$\frac{n-1}{n}=\frac{\ln \left(T_{\mathit{out}}\right)-\ln \left(T_{\mathit{in}}\right)}{\ln \left(p_{\mathit{out}}\right)-\ln \left(p_{\mathit{in}}\right)}$$

Furthermore, the following mathematical relationships apply: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\omega }_r{T}_e$$

$$\frac{n-1}{n}=\frac{\ln \left(T_{\mathit{out}}\right)-\ln \left(T_{\mathit{in}}\right)}{\ln \left(p_{\mathit{out}}\right)-\ln \left(p_{\mathit{in}}\right)}$$

wobei k = ΔV/(2π) ist.For an adiabatic compression cycle, the power P ₂ is thus as follows: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=k_0{\omega }_r{p}_{\mathit{in}}\ln \left(\frac{p_{\mathit{out}}}{p_{\mathit{in}}}\right)+{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_1{\mathrm{<figure-callout\; id="2"\; label="\omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}}_r^{}+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_2{\mathrm{<figure-callout\; id="3"\; label="\omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}}_r^{}$$

where k = ΔV / (2π) .

wobei k = ΔV n/(n-1) /(2π), wobei n eine Konstante ungleich 1 ist, die den Wärmefluss während der Kompression beschreibt. Wenn der Prozess unter konstanter Temperatur abläuft, kann somit n ebenfalls als konstant angenommen werden. Der Ausdruck n/(n-1) ergibt sich aus folgender Gleichung: $$T_{\mathit{out}}=T_{\mathit{in}}{\left(P_{\mathit{out}}/P_{\mathit{in}}\right)}^{\left(n-1\right)/n}$$

In the event that no adiabatic process takes place in the compressor circuit, the power can be specified as follows: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=k_0{\omega }_r{p}_{\mathit{in}}\left({\left(\frac{p_{\mathit{out}}}{p_{\mathit{in}}}\right)}^{\frac{n-1}{n}}-1\right)+{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_1{\mathrm{<figure-callout\; id="2"\; label="\omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}}_r^{}+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_2{\mathrm{<figure-callout\; id="3"\; label="\omega \; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega \; </figure-callout>}}_r^{}.$$

where k = ΔV n / (n-1) / ( 2π ), where n is a non-1 constant that describes the heat flow during compression. If the process runs under constant temperature, then n can also be assumed to be constant. The expression n / ( n -1) is given by the following equation: $$T_{\mathit{out}}=T_{\mathit{in}}{\left(P_{\mathit{out}}/P_{\mathit{in}}\right)}^{\left(n-1\right)/n}$$

This means that this expression can be determined from the temperatures T _in and T _out and the pressures P _out and P _in as follows: $$\frac{n-1}{n}=\frac{\ln \left(T_{\mathit{out}}\right)-\ln \left(T_{\mathit{in}}\right)}{\ln \left(p_{\mathit{out}}\right)-\ln \left(p_{\mathit{in}}\right)}$$

The engine power P ₁ can be monitored in an analogous manner as indicated above by equation (8).

Based on Fig. 4 is the inventive method for a refrigerator shown consisting of a motor 1c, a positive displacement pump 2c, whose output is applied to an evaporator 3c, which is connected via a throttle 4c to a capacitor 5c, whose Output is connected to the input of the pump 2c line connected. The refrigerator is marked 7c.

• T_i ∼ Temperatur am Austritt des Verdampfers 3c
• T_h ∼ Temperatur am Eintritt des Kondensators 5c
• T_box ∼ Temperatur im Kühlraum 7c
• T_amb ∼ Umgebungstemperatur
• Q ₁ ∼ Kühlleistung
• Q ₂ ∼ an die Umgebung abgegebene Leistung
• W ∼ von der Pumpe 2c abgegebene Leistung
• ω_r ∼ Geschwindigkeit der Motorwelle [U/sec]
• T_e ∼ Drehmoment [Nm]
• P₂ ∼ vom Motor abgegebene mechanische Leistung

In this system the following variables result:

• T _i ~ temperature at the outlet of the evaporator 3 c
• T _h ~ temperature at the inlet of the condenser 5c
• T _box ~ temperature in the refrigerator 7c
• T _amb ~ ambient temperature
• Q ₁ ~ cooling capacity
• Q ₂ ~ Power delivered to the environment
• W ~ output from the pump 2c
• ω _r ~ motor shaft speed [rev / sec]
• T _e ~ torque [Nm]
• P ₂ ~ mechanical power output by the engine

$$T_{\mathit{eq}}=\frac{T_h-T_l}{T_l}\cdot \left(T_{\mathit{amb}}-T_{\mathit{box}}\right)$$

These are in the following mathematical context: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\omega }_r{T}_e$$

$$T_{\mathit{eq}}=\frac{T_H-T_l}{T_l}\cdot \left(T_{\mathit{amb}}-T_{\mathit{box}}\right)$$

$$P_3=R_{\mathit{th}}\cdot \frac{T_h-T_l}{T_l}\cdot \left(T_{\mathit{amb}}-T_{\mathit{box}}\right)$$

The area describing the power of the motor 1c as shown in FIG. 14 corresponds to that of FIG. 12 in FIG Fig. 3 or representation 8 in Fig. 2a For the areas P ₂ and P ₃ defining areas, the following relationships arise: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=R_{\mathit{th}}\cdot \frac{T_H-T_l}{T_l}\cdot \left(T_{\mathit{amb}}-T_{\mathit{box}}\right)+K_{\omega }\cdot {\omega }^3$$

$${\mathrm{<figure-callout\; id="3"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_3=R_{\mathit{th}}\cdot \frac{T_H-T_l}{T_l}\cdot \left(T_{\mathit{amb}}-T_{\mathit{box}}\right)$$

The equation 15 describes the power P ₂ at the input of the compressor whereas the equation 17, the power at the output describes the compressor. As illustrated in particular in FIG. 17, the areas to be determined here for determining the power at the interfaces of the functional units may be two-dimensional or multi-dimensional. The area according to illustration 17 is two-dimensional, ie a line. The other surfaces shown here are all three-dimensional. It is understood that these surfaces may possibly be more than three-dimensional, depending on the type of machine to be monitored and the underlying mathematical physical relationships.

Again, the monitoring is carried out in an analogous manner by determining the power at the interfaces of the functional units surfaces according to representations 14, 15 and 17 at time t ₁ and after a time interval at time t ₂ (then resulting in the surfaces according to the Representations 14 '15' and 17 '), to then determine by determining the distance of the surfaces or the volume spanned therebetween, which of the functional units 1 c, 2 c, by which degree have fallen in their efficiency.

• q ∼ Volumenstrom des durch die Leitung 22 strömenden Wassers
• ṁ_g ∼ Abgasmasse
• T_w,out ∼ die Temperatur des aus der Leitung 22 austretenden Wassers
• T_w,in ∼ die Temperatur des in die Leitung 22 eintretenden Wassers
• T_g.out ∼ die Temperatur des Abgases am Austritt
• T_g.in ∼ die Verbrennungstemperatur
• T_amb ∼ die Umgebungstemperatur
• P₁ ∼ die durch den Brennstoff in das System eingebrachte Leistung
• P₂ ∼ die durch das Wasser aus dem System abgeführte Leistung

Finally, based on Fig. 5 illustrated how the monitoring method according to the invention is applicable to the primary circuit of a heating system. The heating system has a burner 20, which heats water in a combustion chamber 21 in a line 22. The heated water from the burner 20 is guided in the primary circuit of the heating system and passes after dissipating its heat in a heat exchanger 23, in which the exiting the combustion chamber 21 exhaust gas gives off its heat to the water. The exhaust gas passes through the outlet 24 into the open. The variables of this system are:

• q ~ volume flow of the water flowing through the conduit 22
• ṁ _g ~ exhaust gas mass
• T _{w, out} ~ the temperature of the emerging from the line 22 water
• T _{w, in} ~ the temperature of entering the line 22 water
• T _g.out ~ the temperature of the exhaust gas at the outlet
• T _g.in ~ the combustion temperature
• T _amb ~ the ambient temperature
• P ₁ ~ the power introduced into the system by the fuel
• P ₂ ~ the power dissipated by the water from the system

in der p_w die Dichte des Wassers und C_pw die spezifische Wärmekapazität des Wassers darstellen. Die zu berechnenden Flächen ergeben sich. hierbei wie folgt und sind zum Zeitpunkt t₁ durch die Darstellung 16 und zum Zeitpunkt t₂ durch die Darstellung 16' angegeben: $$P_2=\overline{P_1}-{\bar{\dot{m}}}_g{C}_{\mathit{pg}}{T}_{w,\mathit{in}}-{\bar{\dot{m}}}_g{C}_{\mathit{pg}}\left({\bar{T}}_{g,\mathit{in}}-T_{w,\mathit{out}}\right)e^{\frac{\mathit{UA}}{{\bar{\dot{m}}}_g{C}_{\mathit{pg}}}-\frac{\mathit{UA}}{{{\mathit{qp}}_w\mathit{C}}_{\mathit{pw}}}}+{\bar{\dot{m}}}_g{C}_{\mathit{pg}}{\bar{T}}_{\mathit{amb}}$$

wobei C_pg und C_pw die spezifische Wärmekapazität des Abgases, U der Wärmeübertragungskoeffizient und A die Wärmeübertragungsfläche zwischen dem Brenner 20 und der Leitung 22 sind. Dabei werden die durch das Abgas abgeführte Leistung P _in und der Massestrom ṁg des Abgases als konstant angenommen, ebenso die Umgebungstemperatur T _amb . Ggf. können diese Größen auch in einfacher Weise durch Messung ermittelt werden.This results in the following relationships: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\rho }_w{\mathit{q\; C}}_{\mathit{pw}}\left(T_{w.\mathit{out}}-T_{w.\mathit{in}}\right)$$

where p _{w is} the density of the water and C _{pw is} the specific heat capacity of the water. The areas to be calculated arise. in this case as follows and are indicated at time t ₁ by representation 16 and at time t ₂ by representation 16 ': $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=\stackrel{~}{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}-{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}{T}_{w.\mathit{in}}-{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}\left({\tilde{T}}_{G.\mathit{in}}-T_{w.\mathit{out}}\right)e^{\frac{\mathit{UA}}{{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}}-\frac{\mathit{UA}}{{{\mathit{qp}}_w\mathit{C}}_{\mathit{pw}}}}+{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}{\tilde{T}}_{\mathit{amb}}$$

where C _pg and C _{pw are} the specific heat capacity of the exhaust gas, U is the heat transfer coefficient and A is the heat transfer area between the burner 20 and the conduit 22. In this case, the power dissipated by the exhaust gas P _in and the mass flow m ' g of the exhaust gas assumed constant, as well as the ambient temperature T _amb . Possibly. These sizes can also be determined in a simple manner by measurement.

As the above exemplary embodiments make clear, the method according to the invention can be used in a wide variety of devices, such as Aggregates, machines and equipment are used, which advantageously always the multi-dimensional surfaces are determined, each defining the power at the interfaces of the functional units to each other in any operating point and thus give a reliable measure of the performance of the functional units and appropriate evaluation of the entire device if they are compared with each other at different times (eg, t ₁ and t ₂ ). It is understood that the times t ₁ and t _{2 are} here to be understood as examples only, expediently the values determined at time t ₁ always remain stored in order to be able to compare them with later ones, which however does not rule out that intermediate values are also stored if necessary, also to record the speed of the change. This too can be evaluated in a corresponding evaluation device. In that regard, in particular EP 1 564 411 A1 referred where comparable evaluations are described in detail.

It should be noted at this point that in the exemplary embodiments illustrated above, two-dimensional or more-dimensional surfaces have always been used to determine the power balance at the interfaces of the functional units, since this allows an evaluation virtually independent of the respective operating point. At substantially constant operating points, these evaluations can also be simplified by comparing individual quantities at intervals with each other, via which conclusions can be drawn about the efficiency indirectly or directly. The two- or multi-dimensional surfaces in question are advantageously determined during operation, whereby it is attempted by suitable iteration methods to achieve a high accuracy of the surfaces on the basis of as few as possible different operating points. This can be achieved in particular by using the Kámán filter, as has already been described above. It however, other suitable iteration methods may be used. It is also conceivable that, for example, in a pump unit, certain operating points are approached targeted to capture the power balance representing surface area with the highest possible accuracy or to dispense with targeted detection of defined operating points on the determination of such areas.

Claims (18)

1. A method for monitoring an energy conversion device which consists of several function units which are functionally linked to one another, in which power-dependent variables of at least one function unit are automatically detected and/or computed in temporal intervals, and are compared to one another or to values derived therefrom and/or to predefined values, and a corresponding signal is produced in dependence on the comparison, characterised in that power-dependent variables of at least two function units which are functionally linked to one another are detected and/or computed, in an automatic manner in temporal intervals, wherein the power-dependent output variables or variables derived therefrom, of the one function unit, form the power-dependent input variables of the function unit which is functionally arranged after this.
2. A method according to claim 1, characterised in that the comparative values or comparative functions are formed by way of power-dependent variables, which are envisaged and suitable for power comparison which is independent of the operating point.
3. A method according to claim 1 or 2, characterised in that it is used for operational optimisation and/or for monitoring the energy consumption or the efficiency of the pump assembly, in particular of an electromotorically driven centrifugal pump assembly, in which on operation, at least one power-dependent variable of the motor and at least one hydraulic variable of the pump or at least two hydraulic variables of the pump, at a temporal interval, are compared to one another or are mathematically linked to one another or compared to predefined values, and a signal characterising the operating condition of the pump assembly is produced in dependence on the comparison.
4. A method according to claim 3, characterised in that it is carried out during the designated delivery operation.
5. A method according to one of the preceding claims, characterised in that it is repeated in temporal intervals, wherein the comparison is carried out on the basis of the previously detected variables or the predefined values.
6. A method according to one of the claims 3 to 5, characterised in that firstly electrical variables of the motor determining the power uptake of the motor, and at least one variable determining the hydraulic operating point of the pump are detected and stored, and in a temporal interval, on reaching a hydraulic operating point corresponding to the previously detected one, the electrical variables of the motor which determines the power uptake of the motor are detected and compared to the firstly stored variables, whereupon a corresponding signal is produced.
7. A method according to one of the claims 3 to 6, characterised in that firstly electrical variables of the motor which determine the power uptake of the motor and variables determining the hydraulic operating point of the pump are detected and stored, and in which these variables are detected anew after a temporal interval, wherein the detected variables are transferred on the basis of a mathematical, electrical motor model and/or a mathematical hydraulic pump model and then compared to the stored variables, or vice versa, whereupon a corresponding signal is produced.
8. A method according to one of the claims 3 to 7, characterised in that the detection of power-determining variables of the motor and/or pump is not effected until after the completion of a predefined time which corresponds at least to the running-in phase of the pump assembly.
9. A method according to claim 8, characterised in that after completion of the predefined time, during the monitoring phase, automatically at least one operating profile is detected and the expected energy consumption is determined whilst taking into account the efficiency change which is possibly determined.
10. A method according to one of the preceding claims, characterised in that a surface course which has a multidimensional model character and is dependent on the power of a function unit is determined on the basis of several operating points and stored, and such surface courses are determined anew in temporal intervals and are compared to the previously determined ones.
11. A method according to claim 10, characterised in that the distance of the surface courses at a predefined operating point, or the volume spanned between the surfaces is used as a measure for the efficiency change, in particular an efficiency drop.
12. A method according to claim 11, characterised in that a Kalman filter is used for determining the surface course on the basis of the operating points.
13. A centrifugal pump assembly with an electrical motor and a centrifugal pump driven by this, characterised in that a device for monitoring the power characteristics of at least one function unit of the assembly is provided, said device operating according to a method according to one of the preceding claims.
14. A compressor assembly with an electrical motor and a displacement pump driven by this, characterised in that a device for monitoring the power characteristics of at least one function unit of the assembly is provided, said device operating according to a method according to one of the preceding claims.
15. A cooling assembly with an electric motor, with a displacement pump driven by this, with an evaporator and with a condenser, characterised in that a device for monitoring the power characteristics of at least one function unit of the assembly is provided, said device functioning according to a method according to one of the preceding claims.
16. A heating facility with a combustor and at least one water circuit which can be heated by this, characterised in that a device for monitoring the power characteristics of at least one function unit of the facility is provided, said device operating according to a method according to one of the preceding claims.
17. An assembly or facility according to one of the preceding claims, characterised in that after a predefined time after starting operation of the assembly or facility, the device automatically begins with the detection and storage of the variables which are relevant to determining the efficiency.
18. An assembly or facility according to claim 17, characterised in that the device comprises a measured value memory, in which at least the variables detected at the beginning of the measurement or variables derived therefrom are stored.

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